Not much to say. Star craft II: Wings of Liberty for $50. Delivery is free (at least I paid none).
This is the cheapest I've seen it (where it has actually been in stock and available for purchase). Normally goes for $65-$100. Dick Smith have sold this at this price only once before to my knowledge.
Rough listing of current prices: http://www.myshopping.com.au/PR--151420_Starcraft_2_Strategy…
Next nearest (that I've ever found): http://www.game.com.au/starcraft-ii-wings-of-liberty/pc-game… ($65 inc delivery)
PLEASE NOTE: Sold out online, again. Stock may be available at your local Dick Smith (or it might flop back into availability online - it has done once before). You can check stock levels online.
I thought it had been at this price point for ages (at least whenever advertised as cheap).